WASHINGTON — The top members of the Senate Armed Services Committee have called for a federal audit of the Pentagon's "military information support operations" in light of concerns about their growing cost and questionable merit, according to their offices and documents obtained by USA Today.

The Government Accountability Office (GAO) review, which begins this week at the request of Carl Levin, D-Mich., and John McCain, R-Ariz., is the latest inquiry into programs the military uses to market its war aims abroad.

"The committee became aware of the (Pentagon's) growing expenditures in this area and its inability to adequately measure the results of its investments, so the committee asked for a GAO review of these activities," Tara Andringa, a spokeswoman for Levin, said Monday in an email.

In February, USA Today reported that spending on information operations peaked at $580 million in 2009, mostly for the wars in Iraq and Afghanistan. Spending fell to $202 million last year, as U.S. participation in the Iraq War ended. The military says tracking effects of information operations is challenging but has improved.

The GAO will audit information operations throughout the military as well as in the National Security Agency, State Department and Central Intelligence Agency, an attachment to the GAO's letter to Defense Secretary Leon Panetta said. Among the key questions: spending on information operations and evaluating their results.

McCain spokesman Brian Rogers said the request is one of the senators efforts to make sure "taxpayer dollars are being spent prudently."

The Pentagon promised full cooperation to ensure the audit is finished quickly, said Lt. Col. James Gregory, a spokesman.

"We welcome the opportunity to allow our programs and activities to speak for themselves, and we are confident that the resulting study will demonstrate the effectiveness of MISO programs and their value to the overall (Pentagon) effort to keep the nation safe," Gregory said.

Last week, the House Defense Appropriations Subcommittee voted to strip nearly $81.5 million of $251.6 million requested by the Pentagon for information operations. Rep. Norm Dicks of Washington, the ranking Democrat on the committee, backed the cut, citing his concern about the lack of details justifying the activities and their benefits.

Sens. Tom Carper, D-Del., and Tom Coburn, R-Okla., and Rep. John Tierney, D-Mass., have also expressed concerns about the programs, especially the $4 million in unpaid taxes by the owners of the Pentagon's top information operations contractor. The Pentagon Inspector General has begun a criminal inquiry, although Leonie Industries' owners have paid their tax bills, company officials say.